Airlift pump

ABSTRACT

An airlift pump comprising a hollow, cylindrical main body having an injection hole near the bottom end, a channel routed in the outside surface of the main body and running continuously from the injection hole to the top end, and an air tube seated in the channel and bonded to the main body. The air tube comprises an injection end having an elbow forming an injection angle such that the air is injection into the main body in a downward direction toward the bottom end. The air tube further comprises a receiving end extending past the top end of the main body and connecting to air supply tubing. The pump has a restricted lateral width enabling the pump to fit inside the narrow monitoring wells typical in the groundwater monitoring industry.

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/956,134 filed on Aug. 16, 2007; Ser. No. 60/979,403 filed on Oct. 12, 2007; Ser. No. 60/979,404 filed on Oct. 12, 2007; and Ser. No. 61/021,616 filed on Jan. 16, 2008.

BACKGROUND OF THE INVENTION

The airlift pump device described herein relates generally to the recovery of subsurface liquid or semi-liquid material. An airlift pump generally comprises a hollow, cylindrical main body connected to a drainage conduit. The main body is submerged into a subsurface liquid or semi-liquid material, causing the interior of the main body to fill with such material. A gas such as air is then introduced into the main body, thereby reducing the specific gravity of the material in the upper part of the main body, which causes that material to become buoyant. As the buoyant material moves upward toward the ground surface, additional liquid material is drawn into the bottom end of the main body, causing a continuous pumping action.

The present device comprises an improved airlift pump for use in the groundwater monitoring industry. This industry uses standard monitoring wells having a relatively small diameter, and prior airlift pumps were difficult, if not impossible, to operate in such tight confines. In addition, operation of prior airlift pumps required expensive customized equipment because these pumps could not accommodate the hoses, fittings, and other pumping equipment standard in the industry.

The device disclosed herein seeks to overcome these problems by providing an improved airlift pump comprising features that optimize performance in the confines of narrow wells. The simplified features and operation of the device permit a significant cost savings over the current pumping methods.

SUMMARY OF THE INVENTION

The airlift pump device generally comprises a hollow, cylindrical main body having an open top end and an open bottom end, and an air tube. The main body has a connection means near the top end. The connection means forms a substantially watertight connection between the main body and discharge tube. An injection hole is located near the bottom end at a distance that can range approximately from one to two and one half inches from the edge of the bottom end. The outside of the main body further comprises a routed channel or elongated recess for seating and retaining the air tube, and the channel runs continuously along the outside of the main body to the top end.

The air tube is a metal tube having a receiving end and an injection end, with the injection end further comprising an elbow forming an injection angle such that the air is injected into the main body in a downward direction toward the bottom end rather than in an upward direction toward the top end. The injection end of the air tube is inserted into the injection hole, and the air tube is seated inside and along the channel in a manner such that the receiving end of the air tube extends past the top end of the main body. The air tube is then secured to the main body by a bonding means, which is any means for securing the air tube to the main body using non-contaminating materials that provide a streamlined shape, such as an adhesive, an epoxy, or a weld.

In use, standard air supply tubing is attached to the receiving end of the air tube, and standard discharge tube is attached to the connection means of the main body. When air is introduced into the air tube via the air supply tubing, the air travels down the air tube, past the elbow, and into the interior portion of the main body at a downward angle. The injected air reduces the specific gravity of the material inside the main body above the injection hole, thus causing this column of material to become buoyant and move upward toward the discharge tube. As this column of material moves, additional material is drawn into the main body via the bottom end, and this continuous action drives the pump.

In another embodiment of the pump, the main body is comprised of a thin-walled metal tube that does not comprise a channel. Instead, the air tube is bonded directly to the outside surface of the main body, with the other features remaining the same. In another embodiment, the connection means comprises a thread insert to accommodate a standard fitting. In another embodiment, the receiving end of the air tube comprises a slight bend forming a deviation angle to accommodate the standard fittings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an oblique view of the air tube and main body, showing the air tube as separated from the main body.

FIG. 2 is a cross section of the improved airlift pump having air supply tubing attached to the receiving end of the air tube and discharge tube attached by a fitting.

FIG. 3 is a cross section of the connection means, showing a standard fitting attached by a threaded insert.

FIG. 4 is a side view of an embodiment where the air tube is attached to the outside surface of the main body by a continuous weld.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, the invention will now be described with regard for the best mode and the preferred embodiment. In general, the device is an airlift pump, specifically modified and improved for use in the groundwater sampling industry. The pump is improved to fit inside standard well sizes using equipment standard in the industry, and it is fabricated from materials that will not contaminate the groundwater sample. Notably, the improved pump will work with a variety of subsurface liquids or semi-liquids, including water, oil, liquid contaminants, or substantially aqueous mud, silt and sand. Although the following discussion illustrates the pump in the context of groundwater sampling, the embodiments disclosed herein are meant for illustration and not limitation of the invention. An ordinary practitioner will understand that it is possible to create variations of the following embodiments without undue experimentation.

Referring to FIGS. 1 and 2, the device generally comprises a hollow, cylindrical main body 10 having a wall, an open top end 11 and an open bottom end 12, and an air tube 13. The main body 10, which can be a standard metal pipe, is preferably made of a non-corrosive material that will not contaminate the groundwater sample. Near the top end 11, the main body 10 has a connection means 20 for joining the main body 10 to a discharge tube 21. The connection means 20 forms a substantially watertight connection between the main body 10 and discharge tube 21 through which water, sand, and light gravel exit the main body 10 and are retrieved to the ground surface. An injection hole 14, which is a bore penetrating the wall of the main body 10, is located near the bottom end 12 at a distance 25 that can range approximately from one to two and one half inches from the edge of the bottom end 12. The injection hole 14 is sized for receiving the air tube 13, as described below. The main body 10 preferably comprises a routed channel 15 for seating and retaining the air tube 13. The channel 15 begins at the injection hole 14 and runs continuously along the main body 10 to the top end 11.

The air tube 13 is a thin-walled tube preferably composed of metal, such as stainless steel for example. The air tube 13 has a receiving end 16 and an injection end 17, with the injection end 17 further comprising an elbow 18 having an injection angle 70 such that the air is injected into the main body 10 in a downward direction toward the bottom end 12 (as shown in FIG. 2) rather than in an upward direction toward the top end 11. In most instances, the injection angle 70 will be within the range of approximately 30 to 70 degrees off of the longitudinal axis of the air tube 13, as shown in FIG. 1. It is preferable that the injection angle 70 lies within the range of about 35 to 55 degrees. The injection angle 70 permits the air tube 13 to be cleaned by inserting a wire into the receiving end 16 and forcing the wire through the air tube 13 until it emerges from the injection end 17. If the injection angle 70 is more than 70 degrees, then any debris or blockage inside the air tube 13 is unlikely to be removed in this manner, instead becoming impacted inside the air tube 13. If the injection angle 70 is less than 30 degrees, then the performance of the pump is reduced to a suboptimal level.

The injection end 17 is inserted into and through the injection hole 14, and the air tube is seated inside and along the channel 15 in a manner such that the receiving end 16 of the air tube 13 extends past the top end 11 of the main body 10, and such that the injection end 17 extends into the interior of the main body 10. This extension permits the air to be introduced into the main body 10 at a location closer to its central axis, thus enabling a more uniform dispersion of air, which may lead to a more optimal performance.

After the air tube 13 is seated in the channel 15, the air tube 13 is then secured to the main body 10 by any means for securing the air tube 13 to the main body 10 in a manner providing a streamlined shape, preferably by a bonding means 19. For example, a tungsten inert gas (TIG) weld serves as an adequate bonding means 19 because this weld is well suited for thin-walled metal tubing, such as that used for the air tube 13, especially where the metal tubing is stainless steel. In addition, a TIG weld does not use silver acetate material, which can contaminate groundwater samples. A continuous bonding means 19, such as a full length continuous weld, is preferable because it provides a streamlined shape, thus reducing the propensity for the pump to become entangled or snagged inside the tight-fitting monitoring wells typical in the industry. Although a spot weld can result in irregularities potentially causing entanglements inside the monitoring well, in some instances a streamlined spot weld can constitute an adequate bonding means 19, specifically where the well diameter is relatively large compared to the lateral width 23 of the pump. The lateral width 23 is the widest lateral dimension of the overall pump measured perpendicular to the longitudinal axis of the main body 10. Thus, the lateral width 23 is the diameter of the main body 10 plus the greatest distance that the air tube 13 laterally protrudes from the outside surface of the main body 10.

In use, standard air supply tubing 22 is attached to the receiving end 16 of the air tube 13, and a standard discharge tube 21 is attached to the main body 10. The pump is then inserted into a monitoring well to the desired depth, with the bottom end 12 below the water surface. An air compressor at the ground surface forces air through the air supply tubing 22 and into the air tube 13. The air travels down the air tube 13, past the elbow 18, and into the interior portion of the main body 10 in a downward direction at the injection angle 70. The injected air reduces the specific gravity of the material inside the main body 10 above the injection hole 14, thus causing this column of material to become buoyant and move upward toward the discharge tube 21. As this column of material moves, additional material is drawn into the main body 10 via the bottom end 12, and this continuous action drives the pump.

Referring to FIGS. 1-3, one embodiment of the pump is intended for use inside a standard groundwater monitoring well having a diameter of at least two inches. In this embodiment, the main body 10 is a metal pipe selected from a schedule of standard pipe sizes, and the lateral width 23 is two inches or less. The injection hole 14 may be located at a distance 25 of approximately one and one half inches from the bottom end 12, and the injection angle 70 of the elbow 18 may be approximately 45 degrees. The air tube 13 is seated in the channel as described above, and the bonding means 19 is a continuous TIG weld. The injection end 17 of the air tube 13 protrudes into the interior portion of the main body 10. The connection means 20 comprises female threads 71 integral to the inside surface of the main body 10 near the top end 11. The discharge tube 21 uses a standard fitting 72 having male threads mating to the female threads 71 (FIG. 2), thus forming a substantially watertight connection. For example, one such fitting 72 is a hose barb to male thread pipe fitting. In another emulation of this embodiment, the receiving end 16 of the air tube 13 embodies a deviation angle 73 falling within the range of approximately 5 to 30 degrees. The deviation angle 73, shown in FIG. 4, allows space for the discharge tube 21 and air supply tubing 22 to be secured in the proximity of the fitting 72.

In another emulation of this embodiment, shown in FIG. 3, the standard pipe selected as the main body 10 can have an inside diameter substantially larger than the diameter of the male threads on the standard fitting 72. In these instances, a coiled wire thread insert 40 is used to reduce the inside diameter of the main body 10, thus providing properly sized female threads 71 to mate with the male threads of the standard fitting 72. By way of example, one such thread insert 40 is the Heli-Coil® thread insert, which is available from Newfrey, LLC.

In another embodiment, the pump is intended for use inside a standard groundwater monitoring well having a diameter of about one inch or more. In this embodiment, the main body 10 is a metal pipe selected from a schedule of standard pipe sizes. The injection hole 14 may be located at a distance 25 of approximately one and one half inches from the bottom end 12, and the injection angle 70 of the elbow 18 may be approximately 45 degrees. The air tube 13 is seated in the channel as described above, and the bonding means 19 is a continuous TIG weld. The lateral width 23 is less than one inch. The connection means 20 comprises female threads 71 integral to the inside surface of the main body 10 near the top end 11. Preferably the female threads 71 are self-tapping. The discharge tube 21 uses a standard fitting 72 having male threads that mate with the female threads 71, and a thread insert 40 can be used where required, as described above.

In another embodiment, shown in FIG. 4, the pump is intended for use inside a standard groundwater monitoring well having a diameter of three quarters of one inch or more. In this embodiment, the main body 10 is a metal pipe selected from a schedule of standard pipe sizes, which embody thin-walled sections. The injection hole 14 may be located at a distance 25 of approximately one and one half inches from the bottom end 12, and the injection angle 70 of the elbow 18 may be approximately 45 degrees. In this embodiment, since the main body 10 is a thin-walled section, there is no channel 15. Instead, the air tube 13 is bonded directly to the outside surface of the main body 10, and the bonding means 19 may be a continuous TIG weld. The lateral width 23 is less than three quarters of one inch. The connection means 20 comprises male threads 50 integral to the outside surface of the main body 10 near the top end 11. These male threads 50 provide a substantially watertight connection to standard fittings 72 for the discharge tube 21. Preferably, the male threads 50 are self-tapping. In this embodiment, the receiving end 16 of the air tube 13 embodies a deviation angle 73 falling within the range of 5 to 30 degrees. The deviation angle 73 allows space for the discharge tube 21 and air supply tubing 22 to be secured in the proximity of the fitting 72.

The embodiments disclosed above are merely representative of the pump and not meant for limitation of the invention. For example, one having ordinary skill in the art would understand that some of the individual features of several disclosed embodiments are interchangeable with the features of other embodiments. Consequently, it is understood that equivalents and substitutions for certain elements and components set forth above are part of the invention, and therefore the true scope and definition of the invention is to be as set forth in the following claims. 

1. An air lift pump comprising: a hollow, cylindrical main body having a top end, a bottom end, and a wall; an injection hole bored through the wall near said bottom end; and an air tube having an injection end, said injection end having an elbow forming an injection angle such that the injection end points downward toward said bottom end, said injection end inserted into and through the injection hole such that the injection end protrudes beyond the wall and into the interior of the main body.
 2. The airlift pump of claim 1, wherein the injection hole is located at a distance from said bottom end such that the air injected into the main body does not exit said bottom end.
 3. The airlift pump of claim 2, further comprising a lateral width of less than two inches, wherein the injection hole is located at a distance from the bottom end within the approximate range of one inch to two and one half inches.
 4. An air lift pump comprising: a hollow, cylindrical main body having a top end, a bottom end, and a wall; an injection hole bored through the wall near said bottom end; a channel beginning at the injection hole and running along the outside surface of the main body to said top end; and an air tube having a receiving end and an injection end, said injection end inserted into the injection hole, said air tube seated in the channel and connected to the main body by a means for continuously bonding the air tube to the main body along the full length of the channel.
 5. The airlift pump of claim 4, wherein the injection hole is located at a distance from said bottom end such that the air injected into the main body does not exit said bottom end.
 6. The airlift pump of claim 5, wherein said means for continuously bonding the air tube to the main body comprises a continuous weld.
 7. The airlift pump of claim 6, further comprising a lateral width of less than two inches, wherein the injection hole is located at a distance from the bottom end within the approximate range of one inch to two and one half inches.
 8. An air lift pump comprising: a hollow, cylindrical main body having a top end, a bottom end, and a wall; an injection hole bored through the wall near said bottom end; a channel beginning at the injection hole and running along the outside surface of the main body to said top end; and an air tube having a receiving end and an injection end, said injection end having an elbow forming an injection angle such that the injection end points downward toward said bottom end, said injection end inserted into and through the injection hole such that the injection end protrudes beyond the wall and into the interior of the main body, said air tube seated in the channel and connected to the main body by a means for continuously bonding the air tube to the main body along the full length of the channel.
 9. The airlift pump of claim 8, wherein the injection hole is located at a distance from said bottom end such that the air injected into the main body does not exit said bottom end.
 10. The airlift pump of claim 9, wherein said means for continuously bonding the air tube to the main body comprises a continuous weld.
 11. The airlift pump of claim 10, further comprising a lateral width of less than two inches, wherein the injection hole is located at a distance from the bottom end within the approximate range of one inch to two and one half inches. 